>>1
What about Dragon Ball, every anime fan saw that one. It was the starting point for many anime otakus. Although I'm kinda joking, you probably already watched it and it's really not that good.
Full Metal Alchemist is win, so you might want to look into that. It was voted the most popular/watched (not sure) anime in japan in a survey by TV ASAHI (sp?), if I'm not mistaken.
Many of the anime series recomended on this thread would make a good start, but if the one you pick does not suit your tastes, remember to not judge anime just for that one serie.
Also posting wich tipe of anime genre you are interested in seeing would be a big help.